Summary

Light rail is a modern form of public transport that runs on rails. It shares many characteristics with heavy rail systems such as metros and suburban rail, but operates with a lower capacity. Its main advantage over these other systems is that it is cheaper and more flexible since it can be operated on the road in mixed traffic. Usually it has a much simpler signalling than heavier rail systems, often relying on the driver's judgement, particularly in mixed traffic conditions. When it is running along a highway it can be given priority at signalised junctions. Light rail can also be elevated or routed through tunnels. Often a combination of these is used to match local circumstances, for example by using disused railway embankments to provide a fast interurban route with street running in town centres.

Despite the substantial capital costs associated with its implementation, light rail is still cheaper than comparable modes (metros and suburban heavy rail schemes). This is reflected in its growth in recent years, with 44 new schemes coming ‘on-line’ in Western Europe and Northern America between 1980-2000 compared with only 9 metro systems. Light rail also tends to outperform metros and heavy rail in terms of fare box recovery (the proportion of operating costs recovered through fares), although to date only one scheme (Manchester Metrolink) fully covers its operating costs.

The objectives behind the development of light rail systems were researched by Mackett and Edwards (1998). They found that stimulating economic development was the foremost reason for implementing light rail systems, closely followed by a desire to ‘improve public transport’ and ‘to reduce traffic congestion’. Less important objectives included improving ‘the environment’ and ‘accessibility to the city centre’.

The building of a light rail system is unlikely to stimulate development on its own but it can form part of a package to facilitate development by providing a modern, efficient way for residents to reach jobs in the city centre; providing city centre access for shoppers and those on leisure trips; and by demonstrating a commitment to the area by various levels of government. In order to implement these concepts there needs to be investment in housing, jobs, shops and leisure facilities. Most of this will be provided by the private sector. The evidence however, suggests that in the case of the Manchester, Sheffield, Baltimore and Los Angeles light rail schemes the impact upon development has been restrained, whilst in St Louis, San Diego, San Jose, Portland, Rouen and Tyne and Wear evidence has been found to support development. In the case of Manchester and Sheffield judgement should be reserved since their implementation was during a recession and the evidence collected only a few months after the opening of the system as opposed to several years after.

Light rail schemes have generally improved public transport in terms of widening the choice and improving the quality of public transport. This may however impact on other modes of public transport, e.g. evidence from Los Angeles suggest that funding was transferred from bus services in the inner city serving low-income households to subsidise the light rail system serving high-income households. In terms of reducing road congestion the evidence suggests that whilst car use has not been reduced there has been a modal shift from car to light rail and the counter factual would have seen larger increases in road congestion.